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991.
Yang Zhang Guowu Zhan Yibo Song Yiping Liu Jiale Huang Shu-Feng Zhou Kok Bing Tan Qingbiao Li 《Frontiers of Chemical Science and Engineering》2022,16(12):1793
Recycling industrial solid waste not only saves resources but also eliminates environmental concerns of toxic threats. Herein, we proposed a new strategy for the utilization of petrochemical-derived carbon black waste, a waste vanadium-bearing resource (V > 30000 ppm (10 −6)). Chemical leaching was employed to extract metallic vanadium from the waste and the leachate containing V was used as an alternative raw material for the fabrication of vanadate nanomaterials. Through the screening of various metal cations, it was found that the contaminated Na+ during the leaching process showed strong competitive coordination with the vanadium ions. However, by adding foreign Ce3+ and Y3+ cations, two rare-earth vanadates, viz., flower-like CeVO4 and spherical YVO4 nanomaterials, were successfully synthesized. Characterization techniques such as scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, Fourier-transform infrared, and N2 physisorption were applied to analyze the physicochemical properties of the waste-derived nanomaterials. Importantly, we found that rare-earth vanadate catalysts exhibited good activities toward the semi-hydrogenation of α,β-unsaturated aldehydes. The conversion of cinnamaldehyde and cinnamic alcohol selectivity were even higher than those of the common CeVO4 prepared using pure chemicals (67.2% vs. 27.7% and 88.4% vs. 53.5%). Our work provides a valuable new reference for preparing vanadate catalysts by the use of abundant vanadium-bearing waste resources. 相似文献
992.
Junjun Li Mi Huang Ping Wei Yaqin Zhang Xuean Zhao Chunbo Liu Zhijun Zhou Lin Zhang 《American Institute of Chemical Engineers》2022,68(3):e17560
Poly(vinyl butyral) (PVB) is selected as a promising ethanol-permselective membrane based on the solubility parameter theory; however, it exhibits anomalous water perm-selectivity in practical pervaporation (PV) process. Comprehensive analysis based on experimental and theoretical methods were carried out to explore the inherent mechanism of the anomalous performance. Firstly, sum frequency generation vibrational spectra and contact angle were developed to quantify the surface reconstruction of membrane in air and ethanol, which indicated that hydrophilic hydroxyl tended to expose on membrane surface with ethanol thus improving the membrane affinity to water. Meanwhile, swelling behaviors proved more water would accumulate in the ethanol swollen membrane. Furthermore, theoretical analysis in terms of sorption and diffusion process, based on the UNIFAC-FV model and Fujita free-volume theory, confirmed the mechanism of anomalous phenomenon of PVB membrane. The comprehensive investigation was expected to provide insights into the basic separation mechanism of PV process. 相似文献
993.
Yuan Cheng Jie Xing Xu Li Lixu Xie Yining Xie Zhi Tan Jianguo Zhu 《Journal of the American Ceramic Society》2022,105(8):5213-5221
Although KNN-based ceramics with high electrical properties are obtained through a variety of strategies, the temperature sensitivity is still one of the key technical bottlenecks hindering practical applications. Here, we use a new strategy, meticulously tailoring phase boundary, to refine the ferroelectric boundary of KNN-based ceramics, leading to high piezoelectricity companied with improving temperature stability. The highest d33 value in this system reaches 501 pC/N with a TC ∼ 240°C, whereas a large strain of ∼0.134% can be kept with 10% lower deterioration until 100°C. The origin of high piezoelectricity is mainly attributed to the well-preserved multiphase coexistence and the appearance of nanodomains, which greatly facilitate the polarization rotation. Instead of the changed intrinsic thermal insensitivity, the precision phase boundary engineering plays an important role in strengthening the temperature stability of electric-induced strain. This work provides a simple and effective method to obtain both high electrical properties and excellent thermal stability in KNN-based ceramics, which is expected to promote the practical applications in the future. 相似文献
994.
Silicon - In the production of multicrystalline silicon solar cell, diamond wire sawing method (DWS) is an important technique, which has already completely replaced multiwire slurry sawing (MWSS)... 相似文献
995.
Synthesis,Structure, and Performance of Efficient Red Phosphor LiNaGe4O9:Mn4+ and Its Application in Warm WLEDs 下载免费PDF全文
Pengfei Li Linling Tan Liping Wang Jiayu Zheng Mingying Peng Yuefei Wang 《Journal of the American Ceramic Society》2016,99(6):2029-2034
For phosphor‐converted warm white light‐emitting diodes (WLEDs), it is essential to find highly efficient red oxide phosphors, which are better chemically stable and benign to environment and can be prepared in a much milder condition. Here, we report a red phosphor LiNaGe4O9:Mn4+ with a quantum yield up to 78% after systematic optimization in synthesis temperature, dopant concentration of Mn4+, and sintering time. Best performance of the phosphor can be reached when it is synthesized in a mild reaction condition, that is, at 850°C for 3 h in air. The integrated emission intensity is more than four times stronger than commercial red phosphor 3.5MgO·0.5MgF2·GeO2:Mn4+ (MFG:Mn4+) under a blue light excitation at 470 nm. Crystal structural analysis reveals that the high efficiency Mn4+ exhibits in the compound is mainly due to the well separation of GeO6 groups from each other by GeO4 tetrahedra in the neighborhood and the ideal substitution of octahedral Ge4+ site by Mn4+ in view of both size and charge matches. The high performance of the phosphor encourages us to apply the blue absorbing red phosphor to WLED, which is based on combination of a blue LED chip and YAG:Ce3+, and the warm perception WLED is therefore achieved with a color temperature of 3353 K. 相似文献
996.
Hor-Yue Tan Ning Wang Masao Takahashi Yigang Feng Hongyun Li Yibin Feng 《International journal of molecular sciences》2016,17(8)
For the first time, we discovered a small proportion of aqueous fraction from Saw Palmetto apart from the fatty acid-rich fraction exhibited pharmacological activity. Therefore, this study aims to explore the anti-tumor potential of red pigmented aqueous fraction of Saw Palmetto, NYG on human hepatocellular carcinoma and its possible targets. Subcutaneous xenograft and orthotopic implantation models of HCC were used to evaluate the tumor inhibitory effect of NYG. Human hepatocellular carcinoma (HCC) cell lines and human umbilical vein endothelial cells (HUVEC) were used as in vitro model. The mRNA expression was conducted by qPCR. Protein expression was monitored by immunoblotting and immunohistochemistry. Cell migration and blood vessel formation were determined by chamber assay and tube formation assay, respectively. Significant tumor inhibition of NYG in dose-dependent manner was observed on subcutaneous xenograft and orthotopic HCC model. NYG has no direct action on cell viability or VEGF secretion of HCC cells. However, NYG reduced in vitro migration and vessel formation activities of HUVEC cells, as well as in vivo intratumoral neovascularization. NYG attenuated extracellular signal-regulated kinases (ERK) activation in endothelial cells, which may be associated with the suppression of migration and tube formation of HUVEC. NYG suppressed tumor expansion of HCC via inhibiting neovascularization, and may be potential adjuvant treatment for HCC. 相似文献
997.
Copper salts, which are abundant, relatively inexpensive and possess low toxicity, have long been used as versatile catalysts for various reactions in organic synthesis. Recently, the development of Cu‐catalyzed or ‐mediated C H functionalization reactions has gained significant attention. Since the pioneering work of Daugulis on the introduction of 8‐aminoquinoline and picolinic acid auxiliaries as removable directing groups in transition metal‐catalyzed C H bond activations, the combination of copper salts with these bidentate directing groups has emerged as an innovative strategy for the construction of carbon‐carbon or carbon‐heteroatom bonds through C H bond cleavage. In addition to the 8‐aminoquinoline and picolinamide systems, several other bidentate directing groups including the 2‐aminophenyloxazoline group by Yu and Dai and the PIP system by Shi, have been developed as well. This review intends to cover most of the recent advances on copper‐catalyzed or ‐mediated direct sp2 and sp3 C H bond functionalizations assisted by these bidentate directing groups. The major achievements in this area are discussed and catalogued by the type of bonds formed (C C, C O, C N, C S, C P etc.). Special attention is paid to the reaction mechanisms. Selected examples of substrates are listed as well. In addition, a personal outlook is given at the end.
998.
Yanliang Zhou Qianjin Sai Zhenni Tan Congying Wang Xiuyun Wang Bingyu Lin Jun Ni Jianxin Lin Lilong Jiang 《中国化学工程学报》2022,43(3):177-184
The industrial manufacture of ammonia (NH3) using Fe-based catalyst works under rigorous conditions. For the goal of carbon-neutrality, it is highly desired to develop advanced catalyst for NH3 synthesis at mild conditions to reduce energy consumption and CO2 emissions. However, the main challenge of NH3 synthesis at mild conditions lies in the dissociation of steady NN triple bond. In this work, we report the design of subnanometer Ru clusters (0.8 nm) anchored on the hollow N-doped carbon spheres catalyst (Ru-SNCs), which effectively promotes the NH3 synthesis at mild conditions via an associative route. The NH3 synthesis rate over Ru-SNCs (0.49% (mass) Ru) reaches up to 11.7 mmol NH3·(g cat)-1·h-1 at 400 ℃ and 3 MPa, which is superior to that of 8.3 mmol NH3·(g cat)-1·h-1 over Ru nanoparticle catalyst (1.20% (mass) Ru). Various characterizations show that the N2H4 species are the main intermediates for NH3 synthesis on Ru-SNCs catalyst. It demonstrates that Ru-SNCs catalyst can follow an associative route for N2 activation, which circumvents the direct dissociation of N2 and results in highly efficient NH3 synthesis at mild conditions. 相似文献
999.
Peng Tan Yao Jiang Qiurong Wu Chen Gu Shichao Qi Qiang Zhang Xiaoqin Liu Linbing Sun 《中国化学工程学报》2022,42(2):104-111
Amines in porous materials have been employed as active species for the selective CO2 adsorption from natural gas because of their target-specific interactions. Nevertheless, it is difficult to modulate such strong interactions to reach a high efficiency in the adsorption processes. Herein, we fabricated light-responsive adsorbents with tunable adsorbent-adsorbate interactions for CO2 capture. The adsorbents were synthesized by introducing primary and secondary amines into a mesoporous silica that had been grafted with azobenzene groups on the surfaces. The target-specific amine sites render the adsorbents significantly selective in the uptake of CO2 over CH4, and the azobenzene groups were used as light-responsive switches to influence the adsorbent-adsorbate interactions. The adsorbents can freely adsorb CO2 when the azobenzene groups are in the trans state. Ultraviolet-light irradiation makes the azobenzene groups transform to the cis configuration, which greatly hinders amines in the uptake of CO2. The caused difference of adsorption capacity can reach 34.9%. The alternative irradiation by ultraviolet- and visible-light can lead to a recyclable regulation on adsorption performance. The changes of the electrostatic potentials of amines are responsible for the light-induced regulation on adsorption. 相似文献
1000.
分析了海水的介电常数与海水温度、盐度之间的关系。讨论了风扰海面的统计特性,给出了风扰海面粗糙度效应和泡沫效应对微波发射贡献的理论及经验模型以及实用的计算风扰海面的发射率和亮度温度表达式。分析了微波辐射计测盐时的测量频率、极化状态及入射角对测量精度的影响。建立了微波航空遥感测量海水盐度的理论及经验模型。指出在温度高于20℃盐度高于10‰,飞机保持平稳飞行,天线角保持恒定的条件下,测量精度可达2‰,取得了比较满意的结果。 相似文献